CODEWITHSUNDEEP
imagematlabbinary
Pier-Alexandre Bouchard
Pier-Alexandre Bouchard

Reputation: 5235

White binary image in Matlab

in Matlab,

if I do:

output = false(5, 5);
imshow(output);

it will show me a black square instead of a white binary square image. Is there any reason to this? How can I output a white binary square?

Upvotes: 1

Views: 366

Answers (3)

Amro
Amro

Reputation: 124553

You could also change the figure's colormap to customize how MATLAB maps values to colors:

BW = [false,true;true,false];
imshow(BW)
set(gcf, 'Colormap',[1,1,1;0,0,0])

screenshot

Upvotes: 1

WebMonster
WebMonster

Reputation: 3031

You could use imcomplement

imshow(imcomplement(false(5, 5)))

or modify the default color mapping (quoting from imshow's documentation)

imshow(X,map)

displays the indexed image X with the colormap map. A color map matrix may have any number of rows, but it must have exactly 3 columns. Each row is interpreted as a color, with the first element specifying the intensity of red light, the second green, and the third blue. Color intensity can be specified on the interval 0.0 to 1.0.

Upvotes: 1

Andrey Rubshtein
Andrey Rubshtein

Reputation: 20915

The reason is that false is mapped to 0, and true is mapped to 1. Also, when showing images, higher number is shown by higher intensity. White has more intensity than black.

Another way to think about it, is that usually you have 256 values - 0-255. 0 is totally black and 255 is totally white. Now, imagine that you do a quantization to two colors. It is now obvious that 0 should be black.

In order to show white square, use 

  output = true(5,5)

Upvotes: 2

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